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397 lines
12 KiB
397 lines
12 KiB
# dialects/sqlite/aiosqlite.py
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# Copyright (C) 2005-2024 the SQLAlchemy authors and contributors
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# <see AUTHORS file>
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#
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# This module is part of SQLAlchemy and is released under
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# the MIT License: https://www.opensource.org/licenses/mit-license.php
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# mypy: ignore-errors
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r"""
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.. dialect:: sqlite+aiosqlite
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:name: aiosqlite
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:dbapi: aiosqlite
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:connectstring: sqlite+aiosqlite:///file_path
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:url: https://pypi.org/project/aiosqlite/
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The aiosqlite dialect provides support for the SQLAlchemy asyncio interface
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running on top of pysqlite.
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aiosqlite is a wrapper around pysqlite that uses a background thread for
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each connection. It does not actually use non-blocking IO, as SQLite
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databases are not socket-based. However it does provide a working asyncio
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interface that's useful for testing and prototyping purposes.
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Using a special asyncio mediation layer, the aiosqlite dialect is usable
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as the backend for the :ref:`SQLAlchemy asyncio <asyncio_toplevel>`
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extension package.
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This dialect should normally be used only with the
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:func:`_asyncio.create_async_engine` engine creation function::
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from sqlalchemy.ext.asyncio import create_async_engine
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engine = create_async_engine("sqlite+aiosqlite:///filename")
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The URL passes through all arguments to the ``pysqlite`` driver, so all
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connection arguments are the same as they are for that of :ref:`pysqlite`.
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.. _aiosqlite_udfs:
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User-Defined Functions
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----------------------
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aiosqlite extends pysqlite to support async, so we can create our own user-defined functions (UDFs)
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in Python and use them directly in SQLite queries as described here: :ref:`pysqlite_udfs`.
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.. _aiosqlite_serializable:
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Serializable isolation / Savepoints / Transactional DDL (asyncio version)
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-------------------------------------------------------------------------
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Similarly to pysqlite, aiosqlite does not support SAVEPOINT feature.
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The solution is similar to :ref:`pysqlite_serializable`. This is achieved by the event listeners in async::
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from sqlalchemy import create_engine, event
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from sqlalchemy.ext.asyncio import create_async_engine
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engine = create_async_engine("sqlite+aiosqlite:///myfile.db")
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@event.listens_for(engine.sync_engine, "connect")
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def do_connect(dbapi_connection, connection_record):
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# disable aiosqlite's emitting of the BEGIN statement entirely.
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# also stops it from emitting COMMIT before any DDL.
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dbapi_connection.isolation_level = None
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@event.listens_for(engine.sync_engine, "begin")
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def do_begin(conn):
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# emit our own BEGIN
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conn.exec_driver_sql("BEGIN")
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.. warning:: When using the above recipe, it is advised to not use the
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:paramref:`.Connection.execution_options.isolation_level` setting on
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:class:`_engine.Connection` and :func:`_sa.create_engine`
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with the SQLite driver,
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as this function necessarily will also alter the ".isolation_level" setting.
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""" # noqa
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import asyncio
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from functools import partial
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from .base import SQLiteExecutionContext
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from .pysqlite import SQLiteDialect_pysqlite
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from ... import pool
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from ... import util
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from ...engine import AdaptedConnection
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from ...util.concurrency import await_fallback
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from ...util.concurrency import await_only
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class AsyncAdapt_aiosqlite_cursor:
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# TODO: base on connectors/asyncio.py
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# see #10415
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__slots__ = (
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"_adapt_connection",
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"_connection",
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"description",
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"await_",
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"_rows",
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"arraysize",
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"rowcount",
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"lastrowid",
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)
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server_side = False
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def __init__(self, adapt_connection):
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self._adapt_connection = adapt_connection
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self._connection = adapt_connection._connection
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self.await_ = adapt_connection.await_
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self.arraysize = 1
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self.rowcount = -1
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self.description = None
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self._rows = []
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def close(self):
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self._rows[:] = []
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def execute(self, operation, parameters=None):
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try:
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_cursor = self.await_(self._connection.cursor())
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if parameters is None:
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self.await_(_cursor.execute(operation))
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else:
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self.await_(_cursor.execute(operation, parameters))
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if _cursor.description:
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self.description = _cursor.description
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self.lastrowid = self.rowcount = -1
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if not self.server_side:
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self._rows = self.await_(_cursor.fetchall())
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else:
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self.description = None
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self.lastrowid = _cursor.lastrowid
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self.rowcount = _cursor.rowcount
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if not self.server_side:
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self.await_(_cursor.close())
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else:
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self._cursor = _cursor
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except Exception as error:
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self._adapt_connection._handle_exception(error)
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def executemany(self, operation, seq_of_parameters):
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try:
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_cursor = self.await_(self._connection.cursor())
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self.await_(_cursor.executemany(operation, seq_of_parameters))
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self.description = None
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self.lastrowid = _cursor.lastrowid
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self.rowcount = _cursor.rowcount
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self.await_(_cursor.close())
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except Exception as error:
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self._adapt_connection._handle_exception(error)
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def setinputsizes(self, *inputsizes):
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pass
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def __iter__(self):
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while self._rows:
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yield self._rows.pop(0)
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def fetchone(self):
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if self._rows:
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return self._rows.pop(0)
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else:
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return None
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def fetchmany(self, size=None):
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if size is None:
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size = self.arraysize
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retval = self._rows[0:size]
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self._rows[:] = self._rows[size:]
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return retval
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def fetchall(self):
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retval = self._rows[:]
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self._rows[:] = []
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return retval
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class AsyncAdapt_aiosqlite_ss_cursor(AsyncAdapt_aiosqlite_cursor):
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# TODO: base on connectors/asyncio.py
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# see #10415
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__slots__ = "_cursor"
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server_side = True
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def __init__(self, *arg, **kw):
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super().__init__(*arg, **kw)
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self._cursor = None
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def close(self):
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if self._cursor is not None:
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self.await_(self._cursor.close())
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self._cursor = None
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def fetchone(self):
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return self.await_(self._cursor.fetchone())
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def fetchmany(self, size=None):
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if size is None:
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size = self.arraysize
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return self.await_(self._cursor.fetchmany(size=size))
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def fetchall(self):
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return self.await_(self._cursor.fetchall())
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class AsyncAdapt_aiosqlite_connection(AdaptedConnection):
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await_ = staticmethod(await_only)
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__slots__ = ("dbapi",)
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def __init__(self, dbapi, connection):
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self.dbapi = dbapi
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self._connection = connection
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@property
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def isolation_level(self):
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return self._connection.isolation_level
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@isolation_level.setter
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def isolation_level(self, value):
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# aiosqlite's isolation_level setter works outside the Thread
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# that it's supposed to, necessitating setting check_same_thread=False.
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# for improved stability, we instead invent our own awaitable version
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# using aiosqlite's async queue directly.
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def set_iso(connection, value):
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connection.isolation_level = value
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function = partial(set_iso, self._connection._conn, value)
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future = asyncio.get_event_loop().create_future()
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self._connection._tx.put_nowait((future, function))
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try:
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return self.await_(future)
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except Exception as error:
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self._handle_exception(error)
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def create_function(self, *args, **kw):
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try:
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self.await_(self._connection.create_function(*args, **kw))
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except Exception as error:
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self._handle_exception(error)
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def cursor(self, server_side=False):
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if server_side:
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return AsyncAdapt_aiosqlite_ss_cursor(self)
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else:
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return AsyncAdapt_aiosqlite_cursor(self)
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def execute(self, *args, **kw):
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return self.await_(self._connection.execute(*args, **kw))
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def rollback(self):
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try:
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self.await_(self._connection.rollback())
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except Exception as error:
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self._handle_exception(error)
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def commit(self):
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try:
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self.await_(self._connection.commit())
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except Exception as error:
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self._handle_exception(error)
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def close(self):
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try:
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self.await_(self._connection.close())
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except ValueError:
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# this is undocumented for aiosqlite, that ValueError
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# was raised if .close() was called more than once, which is
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# both not customary for DBAPI and is also not a DBAPI.Error
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# exception. This is now fixed in aiosqlite via my PR
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# https://github.com/omnilib/aiosqlite/pull/238, so we can be
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# assured this will not become some other kind of exception,
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# since it doesn't raise anymore.
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pass
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except Exception as error:
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self._handle_exception(error)
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def _handle_exception(self, error):
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if (
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isinstance(error, ValueError)
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and error.args[0] == "no active connection"
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):
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raise self.dbapi.sqlite.OperationalError(
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"no active connection"
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) from error
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else:
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raise error
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class AsyncAdaptFallback_aiosqlite_connection(AsyncAdapt_aiosqlite_connection):
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__slots__ = ()
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await_ = staticmethod(await_fallback)
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class AsyncAdapt_aiosqlite_dbapi:
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def __init__(self, aiosqlite, sqlite):
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self.aiosqlite = aiosqlite
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self.sqlite = sqlite
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self.paramstyle = "qmark"
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self._init_dbapi_attributes()
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def _init_dbapi_attributes(self):
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for name in (
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"DatabaseError",
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"Error",
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"IntegrityError",
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"NotSupportedError",
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"OperationalError",
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"ProgrammingError",
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"sqlite_version",
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"sqlite_version_info",
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):
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setattr(self, name, getattr(self.aiosqlite, name))
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for name in ("PARSE_COLNAMES", "PARSE_DECLTYPES"):
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setattr(self, name, getattr(self.sqlite, name))
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for name in ("Binary",):
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setattr(self, name, getattr(self.sqlite, name))
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def connect(self, *arg, **kw):
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async_fallback = kw.pop("async_fallback", False)
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creator_fn = kw.pop("async_creator_fn", None)
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if creator_fn:
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connection = creator_fn(*arg, **kw)
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else:
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connection = self.aiosqlite.connect(*arg, **kw)
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# it's a Thread. you'll thank us later
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connection.daemon = True
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if util.asbool(async_fallback):
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return AsyncAdaptFallback_aiosqlite_connection(
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self,
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await_fallback(connection),
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)
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else:
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return AsyncAdapt_aiosqlite_connection(
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self,
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await_only(connection),
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)
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class SQLiteExecutionContext_aiosqlite(SQLiteExecutionContext):
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def create_server_side_cursor(self):
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return self._dbapi_connection.cursor(server_side=True)
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class SQLiteDialect_aiosqlite(SQLiteDialect_pysqlite):
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driver = "aiosqlite"
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supports_statement_cache = True
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is_async = True
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supports_server_side_cursors = True
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execution_ctx_cls = SQLiteExecutionContext_aiosqlite
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@classmethod
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def import_dbapi(cls):
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return AsyncAdapt_aiosqlite_dbapi(
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__import__("aiosqlite"), __import__("sqlite3")
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)
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@classmethod
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def get_pool_class(cls, url):
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if cls._is_url_file_db(url):
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return pool.NullPool
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else:
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return pool.StaticPool
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def is_disconnect(self, e, connection, cursor):
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if isinstance(
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e, self.dbapi.OperationalError
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) and "no active connection" in str(e):
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return True
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return super().is_disconnect(e, connection, cursor)
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def get_driver_connection(self, connection):
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return connection._connection
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dialect = SQLiteDialect_aiosqlite
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